organic synthesis

Question 1

organic synthesis

Answer 1

process of making organic compounds from simpler starting materials

Question 2

what do we call the compound you want to make

Answer 2

target molecule

Question 3

what are intermediate compounds

Answer 3

compounds that you make on the way to the target molecule

Question 4

what is the purpose of a mechanism

Answer 4

they show how electrons rearrange when a chemical reaction happens

Question 5

is breaking bonds endo or exothermic

Answer 5

endo

Question 6

when bonds are formed is that endo or exothermic

Answer 6

exo

Question 7

how to identify a substitution reaction

Answer 7

start with 2 molecules end up with 2

Question 8

how to identify a addition reaction

Answer 8

start with 2 molecules end up with one

Question 9

how to identify an elimination reaction

Answer 9

start with 1 molecule end up with 2 molecules

Question 10

how to identify a redox reaction

Answer 10

is something gaining or loosing oxygen/ forming double bonds to Oxygen

Question 11

substitution reaction

Answer 11

a chemical reaction in which an atom or group of atoms in a molecule is replaced by another atom or group of atoms

Question 12

what are the 2 substitution reactions

Answer 12

halogenation of alkanes
esterification

Question 13

uses of halogenated alkanes

Answer 13

they do not support combustion so are used as fire extingushers

Question 14

free radical

Answer 14

an atom/ molecule/ group of atoms that contain s unpaired electron

Question 15

how are free radicals presented

Answer 15

a dot

Question 16

how reactive are free radicals

Answer 16

extremely reactive as they do not have a stable outer octet

Question 17

homolytic fission

Answer 17

each atom joined by the bond keeps one of the 2 electrons in the bond

Question 18

write the mechanism for the monochlorination of methane

Answer 18

initiation
propagation
propagation (chain reaction step)
termination

Question 19

evidence for free radical substitution

Answer 19

takes place under UV light- suggests that a free radical mechanism occurs where Cl2 is split into 2 chlorine free radicals

for every photon of light absorbed, thousands of chloromethane molecules form- evidence for chain reaction

small amounts of ethane formed- methyl free radicals combine to form ethane

adding a source of free radicals eg tetraethyllead speeds up the rate of reaction- this decomposes to produce methyl radicals which then increase the rate of the reaction

if an inhibitor is added the rate of the reaction slows down-the inhibitor combines with free radicals to stop the chain reaction from occuring

Question 20

what is hydrolysis?

Answer 20

the reverse reaction of esterification
ie
ester + water —–> alcohol and carboxylic acid

Question 21

saponification

Answer 21

base catalysed hydrolysis of esters with a carboxylate salt is formed

Question 22

describe hydrolysis

Answer 22

a chemical reaction where something reacts with water
the ester reacts with OH- and H+ and the ester breaks apart
a base is a very effective reactant to hydrolyse an ester. the most commonly used us sodium hydroxide

Question 23

addition reaction

Answer 23

a reaction where 2 or more molecules react together to form a single product

Question 24

use of 1,2-dichloroethane

Answer 24

used to make PVC

Question 25

use of 1,2-dibromoethane

Answer 25

used to fumigate logs for termites and beetles

Question 26

use of ethanol

Answer 26

solvent

Question 27

use of chloroethane

Answer 27

used to test for a dead tooth is placed on a tooth and causes cooling. if you cannot feel the cooling the tooth is dead

Question 28

write the mechanism for an addition reaction

Answer 28

polarisation heterolytic fission carbonium ion formation ionic addition

Question 29

evidence for an addition mechanism

Answer 29

a mixture of products is formed when ethene reacts with Br2 in water with sodium chloride dissolved in water 3 possible products can be formed: 1,2-dibromoethane 1-bromo-2-chloroethane 2-bromoethanol

Question 30

how to identify an addition reaction

Answer 30

starting material is unsaturated

Question 31

what does poly unsaturated mean

Answer 31

more than one c double bond c

Question 32

which oils are polyunsaturated

Answer 32

sunflower oil, palm oil, corn oil

Question 33

which fats are saturated

Answer 33

animal fats

Question 34

which fats are unsaturated

Answer 34

vegetable fats (better for your health)

Question 35

what is polymerisation

Answer 35

a type of addition reaction and is how some polymers are formed. 2 c double bond c add together in addition polymerisation

Question 36

what is the unit that polymers are mode up of?

Answer 36

monomers

Question 37

which fraction is used to manufacture a large number of polymers

Answer 37

crude oil

Question 38

what is poly ethene

Answer 38

a synthetic man made polymer formed when many ethene monomers join together by addition polymerisation

Question 39

what does PVC stand for

Answer 39

poly(vinyl chloride)

Question 40

uses of polymers

Answer 40

plastic, nylon

Question 41

what are monomers

Answer 41

building blocks of the polymer they are the starting material that you use to form the polymer. monomers for addition reactions MUST have a double bond

Question 42

polymer

Answer 42

a polymer is a long chain molecule made by joining together many small repeating units/ molecules called monomers

Question 43

repeating unit

Answer 43

part of the polymer that repeats and completes the polymer chain except for the end groups

Question 44

how do you draw the repeating unit of a polymer

Answer 44

draw 3 monomers side by side break the double bond and draw a bond linking each monomer together and the blank bonds on the end carbons place brackets around the whole thing

Question 45

draw the monomer of poly(x)

Answer 45

draw the structure of x

Question 46

what is another name for vinylchloride

Answer 46

chloroethene

Question 47

how do you revert back from the repeating unit to the monomer

Answer 47

remove the bracket put a double bond between the C atoms remove the end bonds

Question 48

draw the synthesis of PVC

Question 49

elimination reaction

Answer 49

a reaction in which a small molecule is removed from a larger molecule and a double bond is formed in the larger molecule

Question 50

what is a dehydration reaction

Answer 50

if the elimination reaction removes water

Question 51

what are some oxidising agents

Answer 51

acidified sodium dichromate acidified potassium permanganate

Question 52

what colour change is observed with acidified sodium dichromate

Answer 52

orange (Cr+6) to green (Cr+3)

Question 53

what colour change is observed with acidified potassium permanganate

Answer 53

purple Mn+7 to colourless Mn+2

Question 54

what is the reducing agent

Answer 54

hydrogen gas over a Ni catalyst

Question 55

what is used to oxidise ethanal is the liver

Answer 55

ethanol

Question 56

explain the oxidation of a primary alcohol to an aldehyde then a carboxylic acid

Answer 56

using an oxidising agent in excess, the primary alcohol will be oxidised into an aldehyde and then further into a carboxylic acid. this can be reversed using H2/Ni

Question 57

explain the oxidation of a secondary alcohol to a ketone

Answer 57

if an oxidising agent reacts with a seondary alcohol a ketone is formed. acidified potassium permanganate is a weak oxidising agents and it is not strong enough to oxidise a ketone further so there is only one oxidation product

Question 58

which functional groups are acidic

Answer 58

alcohols and carboxylic acids

Question 59

are alcohols strong or weak acids

Answer 59

weak acids so they do not react with bases

Question 60

under what circumstances do alcohols react as acids

Answer 60

in the presence of very reactive metals such as sodium

Question 61

what is formed when carboxylic acids react with metals

Answer 61

hydrogen gas

Question 62

what is formed when carboxylic acids react with metal carbonates

Answer 62

salt water and carbon dioxide

Question 63

what is formed when carboxylic acids react with alcohols

Answer 63

esters

Question 64

why do carboxylic acids behave as acids

Answer 64

the inductive effect stability of the carboxylate group

Question 65

what is the inductive effect

Answer 65

where the carbonyl group pulls electron density from the H in the OH group which makes it easier to ionise the OH group to form -COO- and H+

Question 66

what is the stability of the carboxylate ion

Answer 66

if the carboxylic acid group looses a proton it forms a negative ion called a carboxylate ion the negative charge on the carboxylate anion is actually shared/ spread across the 3 atoms. this is called a resonance hybrid and provides extra stability to the ion